When you call, you shout or cry out so that someone can hear you. You might call to a bicyclist who's veering dangerously into traffic.
You can call to your friend across the street, or call him on the phone, and you can also call your new puppy Jack. Your boss might call for new rules about how much time employees take for lunch — in other words, order or instruct her workers. A call can also mean a shout or a phone call — or the decision an umpire makes during a baseball game. The Old English root is ceallian, "to shout."